2884 Bulletin 47, United States National Museum. 



H. Vent anterior; dorsal spines 3 or 4 ; scales ctenoid. 



CV, APHREDODERID.E, 785. 

 HH. Vent normal. 



I. Chin with two long barbels, behind symphysis; dorsal continu- 

 ous, with 5 spines CX VI, POLYMIXIID jc, 854. 



II. Chin without barbels. 



J. Dorsal fin divided, the anterior part of a single slender spine; 



ventrals elongate , .CCXII, BREGMACEROTID^E, 2525. 



JJ. Dorsal fin divided, the anterior part of many spines. 

 K. Body covered with firm serrated scales; anal spines 4; dorsal 



spines not elevated CXV, HOLOCENTRIDJS, 845. 



KK. Body naked or covered with small scales, besides bony plates or 



warts CLXII, ZEID/E, 1659. 



KKK. Body uniformly covered with cycloid scales; dorsal spines 

 mostly very high and filamentous. 



CXXIV, NEMATISTIID.E, 894. 

 JJJ. Dorsal fin continuous, its spines 2 to 8. 



L. Suborbitals narrow, not covering the cheeks. 



CXIV, BERYCID.E, 837. 

 LL. Suborbitals very broad, covering the cheeks. 



CXIII, TRACHlCHTHYIDyE, 836. 



CC. Ventral fins with or without spine, the number of soft rays fewer 



than 5. 



M. Gill opening before the pectoral fin. 

 N. Anal fin present; caudal fin not directed upward. 

 O. Upper jaw not prolonged into a sword. 

 P. Dorsal fin with some spines or simple rays. 

 Q. Dorsal fin without soft rays, composed of spines only. 



CC, BLENNIID^, 2344. 



QQ. Dorsal fin with soft rays anteriorly, with spines posteriorly; 

 gill membranes joined to isthmus. . CCVI, ZOARCID^E, 2455. 

 QQQ. Dorsal fin of spines anteriorly, with soft rays posteriorly. 



R. Dorsal spines all separate and unconnected; body scaleless, 

 naked, or with bony plates; ventral with a sharp spine. 

 XCVIII, GASTEROSTEID.E, 742. 

 RR. Dorsal spines connected by membrane. 



S. Suborbital with a bony stay, extending across the cheek, to or 

 toward the preopercle, the cheek sometimes entirely cov- 

 ered with a coat of mail. 

 T. Pectoral fin divided into 2 parts, 1 of them very long; head 



bony CLXXXVI, CEPHALACANTHID^E, 2182. 



TT. Pectoral fin not divided. 



U. Body entirely covered with an armor of bony plates ; head bony. 



CLXXXI, AGONID^E, 2031. 

 UU. Body naked, or more or less rough or scaly, not entirely covered 



by bony plates. 



V. Gill opening very small, not extending below upper edge of 

 pectoral; skin everywhere prickly; head very large, bony 



above CLXXX, RHAMPHOCOTTID.E, 2029. 



VV. Gill opening large, extending downward nearly or quite to 



lowest pectoral ray.. CLXXIX, COTTID^:, 1879. 



SS. Suborbital without bony stay. 



W. Dorsal spines 2 to 4 only ; head very broad, depressed ; gills 3 ; 



gill membranes broadly united to the isthmus. 

 x. Ventrals each a strong spine ; teeth incisor-like ; scales shagreen- 

 like , CLX VIII, TRIACANTHID M, 1697. 



xx. Ventrals not reduced each to a single spine. 



CXCVIII, BATRACHOIDID^, 2313. 

 WW. Dorsal spines numerous ; gills 4. 



X. Gill membranes separate, free from the isthmus. 

 Y. Body greatly elongate; lower jaw with a slit at base to permit 

 free motion ; lips not fringed. 



